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Was 49b: An Overmassive AGN in a Merging Dwarf Galaxy?

We present a combined morphological and X-ray analysis of Was. 49, an isolated, dual-AGN system notable for the presence of a dominant AGN, Was 49b, in the disk of the primary galaxy, Was 49a, at a projected radial distance of 8. kpc from the nucleus. Using X-ray data from Chandra, the Nuclear Spectroscopic Telescope Array, and Swift, we find that this AGN has a bolometric luminosity of L-bol similar to 10(45) erg s(-1), with a black hole mass of M-BH = 1.3(-0.9)(+10)M(circle dot) . Despite the large mass, our analysis of optical data from the Discovery Channel Telescope shows that the supermassive black hole (SMBH) is hosted by a stellar counterpart with a mass of only 5.6(-2.6)(+4.9)M(circle dot), which makes the SMBH potentially larger than expected from SMBH-galaxy scaling relations, and the stellar counterpart exhibits a morphology that is consistent with dwarf elliptical galaxies. Our analysis of the system in the r and K bands indicates that Was. 49 is a minor merger, with the mass ratio of Was 49b to Was 49a between similar to 1:7 and similar to 1:15. This is in contrast with findings that the most luminous merger-triggered AGNs are found in major mergers and that minor mergers predominantly enhance AGN activity in the primary galaxy.

Identiferoai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/623232
Date17 February 2017
CreatorsSecrest, Nathan J., Schmitt, Henrique R., Blecha, Laura, Rothberg, Barry, Fischer, Jacqueline
ContributorsUniv Arizona, LBT Observ
PublisherIOP PUBLISHING LTD
Source SetsUniversity of Arizona
LanguageEnglish
Detected LanguageEnglish
TypeArticle
Rights© 2017. The American Astronomical Society. All rights reserved.
Relationhttp://stacks.iop.org/0004-637X/836/i=2/a=183?key=crossref.8fe65eb971179ec7cc9f149fbea7f8c0

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